Medline, Embase, the Cochrane Central Register of Controlled Trials (Central) and references of relevant studies were searched.
Longitudinal studies [randomised controlled trials (RCT), clinical trials, cohort-studies and case series] were considered for evaluation. Retrospective studies were excluded. Only case series that investigated at least five patients were considered for inclusion. Outcome measures considered were implant survival, radiographical assessment of marginal peri-implant bone levels, dental-professional-assessed aesthetics, peri-implant biological structures (level of marginal gingiva, papilla index, probing depth, presence of plaque, bleeding on probing), patient satisfaction, and biological and technical complications.
Data extraction and synthesis
Articles were screened independently by two examiners and the following parameters recorded: number of patients, implants placed, dropouts, followup time, type of intervention and details of outcomes. To assess the agreement between the two reviewers on the quality of studies, Cohen's kappa statistic was calculated. A meta-analysis was performed using a statistical software package [Comprehensive Meta-analysis Version 2.2, Biostat, Englewood NJ]. To calculate the overall effects for the included studies, weighted rates together with random effects models were used. Stratification procedures were applied for followup time and type of intervention. No formal heterogeneity testing was conducted.
Nineteen studies were included, of which five were RCT, two were clinical trials and 12 were case series. A meta-analysis showed an overall survival rate of 95.5% 95% confidence interval, 93.0–97.1) after 1 year. A stratified meta-analysis revealed no differences in survival between immediate, early and conventional implant strategies. Little marginal peri-implant bone resorption was found together with low incidence of biological and technical complications. No significant differences in outcome measures were reported in clinical trials comparing immediate, early or conventional implant strategies.
The selected studies provide promising short-term results for immediate, early and conventional single-implants in the aesthetic zone. Important parameters, such as aesthetic outcome, peri-implant structures and patient satisfaction, however, still need further evaluation. The outcome measures could not be fully evaluated when comparing immediate, early and conventional implants because of the lack of RCT.